1. Field of the Invention
The invention relates to a method for controlling an ECM motor to output a constant torque.
2. Description of the Related Art
Electronically commutated motors (ECM) or DC brushless permanent magnet synchronous motors generally have three control modes including a constant rotational speed control mode, a constant torque control mode, and a constant air volume control mode, of which, the constant torque control mode is commonly used. A currently used vector control mode has complicate mathematical model, troublesome operation, high demands on the arithmetic capability of a central processing unit (CPU), thereby resulting in high production costs. A typical constant torque control mode is conducted by scale control of the bus current; however, such a control mode is complicated and has a plurality of variables thereby resulting in poor control accuracy.